The present disclosure relates to an image pickup device of a backside illumination type, to a manufacturing method thereof, and to an electronic apparatus.
In a solid-state image pickup device (an image pickup device) such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a solid-state image pickup element (an image pickup element) including a photoelectric conversion section (for example, a PD (Photo Diode) is arranged for each pixel.
In the image pickup device, when intense light enters some pixels in an imaging screen to allow signal charges to be produced in an amount exceeding charge accommodation ability of a photodiode, the excessive signal charges overflow out of a potential well configured by the photodiode to leak into neighboring photodiodes, which contributes to serious degradation in image quality. The signal charge leak may be prevented, for example, by providing a trench between adjacent pixels in a Si substrate in which the photodiode is embedded, and by covering a surface of the trench with an insulating film having a negative fixed charge.
On the other hand, most image pickup devices have a configuration in which incident light is allowed to enter on the wiring layer side (a front side illumination image pickup device). Disadvantages in such image pickup devices involve lowered sensitivity caused by the incident light shielded by the wiring layer, and occurrence of color mixing caused by the incident light reflected by the wiring layer to enter an adjacent pixel. Accordingly, a backside illumination image pickup device is proposed. In the backside illumination image pickup device, photodiodes and various transistors are provided on a front surface of a Si substrate, and a rear surface of the Si substrate is polished for thinning to allow incident light to enter on the rear surface side for photoelectric conversion (for example, Japanese Unexamined Patent Application Publication No. 2005-209677).
In the backside illumination image pickup device, an external connection electrode on the same layer as the wiring layer is provided on the opposite side (the front surface) to the light-incident surface (the rear surface) of the Si substrate. Therefore, the external connection electrode is exposed as an electrode pad inside a hole with a depth enough to penetrate the Si substrate. The external connection electrode thus exposed is connected to an external circuit, for example, by wire bonding. At this time, an end of a capillary is likely to come into contact with an edge of the hole, which may cause a leak. To cope therewith, proposed is an image pickup device provided with an insulating film around the hole to insulate the external connection electrode from the Si substrate (for example, Japanese Unexamined Patent Application Publication No. 2010-109137).